Grinding machine



Jan. 17, 1928.

W. F. FRASER GRINDING MACHINE Original Filed May 4, 1923 dim-no S r 5 MW Patented den. 1?, i928 UNITED stares insane WARREN FQFRASER, OE WESTBGBU, EEASSAGHUSETTS, ASSIGNGR, BY IMESNE ASSIGN- MENTS, T WORCESTER STEEL PRODUCTS COMPANY, 01? "WORCESTER, I'I'IASSACHU- SETTS, A COBPOEATIOH GE MASSACHUSETTS.

GRINDING MACHINE.

. Application filed May 4, 1923, Serial No. 636,706. Renewed November 15, 1926. v

This invention relates to a machine for grinding cylindrical work such as piston pins, rollers and the like between a pair of plane-surfaced grinding wheels. i v

The principal object of the invention is to improve the grinding machines of this general character which have been designed heretofore and simplify the same, and more specifically to provide an arrangement in which the work itself will not be positively driven but both grinding wheels will be; to provide for rotating the grinding wheels in opposite directions so as to increase the effective speed of the machine without unduly speei'ling up the wheels themselves; to provide for supporting the work in such a manner that the grinding action will be caused bothby the motion of the work out and in along the grinding surfaces and by a relative sliding motion; to provide an even, grinding action on the work; and to provide an even wear on the grinding surfaces. I

liurther objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accoinpanying drawings, in which Fig. l is a side View of a grinding machine constructed in accordance with this invention; Y s liig. 2 is a central sectional view through the rinding elements on the line 2 of l ig. .i; and

lsig. 3 is a plan of the work holding cage.

The invention shown as applied to the type of grinding machine comprising a frame having a horizontalsupport11 near the bottom thereof and provided with a vertical head 12 adjustable on vertical ways near the top. This head is adapted to be raised and lowered by hand and fixed by bolts. It supports a shaft 1% thereon having radiating hand grips 15 by which it may be turned and provided with the necessary gearing, not shown, for raising and lowering the quill 2a which carries the spindlei2l with it. v

The machine is driven from a tight and loose pulley 16 on a shaft 17, the tight pulley driving therefrom two pulleys 18 and 19 respectively. The pulley 19 drives a pulley 20 on the vertical spindle 21 by means of a belt 22 passing over an idler 23 which turns the belt through a quarter turn. This spindle 21 is carried by the slide 12 through a sleeve 2%, below which'isfmounted the upper grinding wheel or stone At the bottom of the spindle is hung a spider 40 positively driven by the spindle but hung loosely so to be free to bemoved up and down slightly independent of the spindle.

The'grinding wheel is fixed tothe spider and rests on the work freely.

'lhe pulley 18 in a similar way drivesa pulley on a vertical hollow shaft 27 carried in stationary hearings on the table 11 at the bottom of the machine. To the upper end of this shaft is fixed a head 28 to which is secured a plate 29 having on it the lower grinding wheel 30. These two grinding wheels andSO are both of annular. coir struction having fiat annular; grinding surfaces located exactly opposite each other. They are arranged concentrically and rotate on concentric axes, in opposite directions and at different speeds. r p V vli iounted in fixed position on the base of the machine and centrally in alignment with the shafts 21 and 27 is afiXed rod 31 extending up through the hollow shaft 27. At the top this rod has a head 32. Therod is fixed in position by a pin 33 at thebottom so that it cannot rotate. {)n the head 32 is mounted 'a-vertical eccentric pin 34. In setting up the device the pin 34 can be located as desired on the head 32 to secure.the desn'ed amount of eccentricity by changing the position of the pin 3%. It is positively fixed at distance from the axes of the shafts 21 and 27. On this eccentric pin 34L is freely rotatable a suitable cage or holder 35 whichcarries a number of pins, rollers or the like 36 to be ground. These pins or rollers constitute the work and they. are-arranged at a small angle to the radial lines;

In the operation of the device the cage is placed in position on the eccentric pin between the two stones or grinding wheels and left freeto rotate about that .pin as a center but obviously it will rotate eccentrically with respect to the two concentric grinding wheels. "The grindingiwlieels may be used with powdered grindingorpolishing matemounted stationary pin 34-.

rials if desired and the full pressure due to the weight of the wheel 25 is exerted on the work. 1

The rotation of the shalt 17 results in rotating the two shafts 21 and 27 in opposite directions preferably at different speeds. Although the two stones thereof are rotated concentrically, their acting surfaces are always at any point moving in opposite directions. The result of this rotation first to rotate the parts being, operated upon and second, because of one grinding ,wl'ieel moving ata fasterspeed than the other, it causes a. slow rotating movement of the entire holder or cage, said cage being entirely tree to rotate about the eccentric-ally The grinding action is due to the factthat the pins or rollers do not have their axial line corresponding with a radial line of the cage but areset at an angle thereto so thatin rotating there is a corresponding sliding action between the rolls and the grinding elements, due to their angular position in the cage. This is the principal grindingaction obtained. However, to obtain extremely accurate work, it is necessary that other actions be obtained in order to insure not only even distribution; of grinding-action onall portions ofthe Work but likewise an even amount of wear on all portions of the grinding elements. The pins or rollsat differentperiods of the grindingoperation should contact with the grinding eleinentat different distances from the center. Thisis accomplished by the rotation of the eccentrically mounted work carrier which in one revolutionfwill bring elen1ents one to the other. rinding elenie'nt rests upon the work solely the rolls that Were-furthest from-the center of the grinding element tothe position of closest approach to the centerptl'ius dis 1 tributingthe worlcof grinding that particular-roll over the entire grinthnglsuriaee ot the grinding elements and at the sarnetinie any given portion of the grinding element operates on diflerentportions of the work. The result is an entire-freedom from lines orjlocal irregularities which would be produced if thesesecondary movements were not present. Thiswould be the case if the work holder was mounted concentrically with thegrinding elements; *The result is that the grindingoperation is accomplished very rapidly and thoroughly and also uniformly.

Also, it will be apparent that the accuracy of the diameters of the-finished work and their parallelism is not dependent initially upon the accuracyof the machine or ext-reins accuracy in the approach ofthe grinding The upper by its own weightand that ofthe spindle and if desired additional weight may be placed thereon, but the movement. is not thousandths of an inch and luuuiuu-iti uin' naaaeeo what would ordinarily be cailed a positiro one, being actuated solely by gravity. This stone is not fed toward the work at all but the grinding operation is continued until the work is reduced to the proper diameter. In operation, therefore, with conditions of action remaining the same it will be fouuiil that a given reduction in diameter will be obtained in a given tinieand therefore the time element is relied upon rather than any ."Ji ncrement of one grinding,- element toward the other. As an example, it the operator finds that two niiiultos of opuiration on a ,g'ivenworli: reduces the diameter hair too or inspecting; the work he liuds that itit one tenthousandths bigger than desired, he would placethc work in the mrurhine urul let it operate for one halt minute and the work would be oi correct site. It canthua be seen thatthis n'iaci'line can he used to commercially prmluce work nuuish closer in its finished dimensions than is obtainable in what conunonly known as ajgrindiup;

inachine and yet at a much more rapid rate W than has been obtainable from what has been commonly known as a lapping uuuihiue.

Upon the completion of the work or the desire to inspectthe progress of the same, turning the hand wheel 15 r al a the upgimr grinding wheel audfallowe inspect J1"! or removal of the work audits cage or holrflar and replacing by another.

Although I have illustrated anddescrihrul only a single iorin oi the invention, I am aware of the fact that niodiiicatirnis can be made thereinby'any person skilled in the art without departing from the scope oi the invention as expressed intheclahns. 'llhcro fore, I do not wish to be hunted to alllhc details (Ti cointruction herein shown and described but whatl do claim hu "i. In a machine of the m-luiractcr dcsurihwl. the roinbiuatirim of a; hollow rotating alzal't, supported in lined heuriup sarul proji 3 upwardly, an annular grinding Wlil'll hunt carried on Muir-oi said shaft and rot ,lihp' concentrieally thcreu'itln a rod im-alezl in fixed POSiliiOli and exteiulinp up through s aid shaft and having; a head on the top above the li upper end oi said shuit, a pin eccentric-idly niounted in stationary position on said head with respect to said slratl't, a circular cage for supporting cylindrical articles to be ground in a position with their axes iua plane, saidpin being adapted to center the cage in position :torsaid cage to project over the top of said stone, and a grinding stone or wheel adapted torest and operate on said work.

2. In a machine of the chararrtar described, the conibination of a stationary lraiue, a table extending tliei-ct'ij-onn a rotating hollow shaft supported. in fixed hearings on said table and projecting up therefrom, an an ii-i baa

nular grinding wheel fiXedly carried on top of said shaft and rotating concentrically therewith, a. rod located in fixed position on said table and extending up through said hollow shaft and having a head onthe top above the upper end of said shaft, a stationary centering pin eccentrically mounted on said head with respect to said shaftand adapted to carry rotatably a circular cage for supporting articles to be ground, in position for said cage to project over the top oi said stone, a vertically movable shaft above the first named shaft and concentric therewith, a grinding stone or wheel carried at the bottom of the upper shaft and adapted to operate on said work, and means or rotating said shafts in OPPOSliO directions a d at ditl'crent speeds.

in a machine of the character described, the combination with a rotary grinding element and a second rotaryagrinding element supported concentrically above the first, of means for rotating them independently upon substantially the same axis, means for holding the work on the surface or the lower grinding element comprising a circular cage in which the work is located, and means for centering said cage on an axis eccentric with respect to the axis of rotation of said grinding elements, said cage being free to be rotated on said axis by the rotation of the grindingelement, saidcage being arranged to hold each piece of work at an angle to the radii oi? the cage, the upper grinding element being supported to be rotated positively but to rest with its weight on the work, whereby the extent of the grinding action will depend on the time duringwhich it is sub iected to it and will be independent o't any :ieeding action.

t. in a machine of the character described,

the combination or a rotating shaft, an an order grinding wheel fixedly carried by said shalt and rotating concentrically therewith, a rod hunted in tired position and having a head on the top above the upper end oi said shalt, a pin ecentrically mounted in stationary position on said head with respect to said shaft, a cage for supporting cylindrical articles to be ground in a position with their axes in a plane, said. pin being adapted to center the cage in. position for said cage to project over the top of said stone, and a grinding stone or wheel adapted to rest and operate on the cylindrical articles. I

5. In a machine of the character described, the combination with a rotary grinding stone having an annular top plane operating surface for supporting the work thereon, of a similar grinding stone over it and the other side up resting at all times "freely by gravity alone on the work, a rotary spindle over said stone, and means for loosely connecting the upper stonewith said spindle to positively rotate it therewith without taking any of its weight oil the work, whereby the extent oi the operation on the work will be measured by the duration of time alone.

(3. In a machine or the character described, the combination of a hollow shaft, supported in fixed bearings and projectin upwardly, an annular grinding wheel fixedly carried on top or said shaft and arranged concentrically therewith, a rod located in fixed position and extending up through said shaft and having a head on the top above the upper end 01'? said chair, a pin eccentrically mounted on said head with respect to said shaft, a circular cage for supporting articles to be ground, aid pin being adapted to center the cage in position for said cage to project over the top of said stone, a shaft above the first named shaft and concentric therewith, and a grinding stone or wheel carried at the bottom of the upper shaft and adapted to rest and operate on said work,

7; In a grinding machine, the combination with two annular horizontal grinding wheels having opposed concentric flat grinding surfaces, means for rotating each or said wheels independently of the other on a vertical axis, and a cage eccentrically mounted with respect to said axis having means for bold ing the work between said stones, said cage being free to turn on its eccentric axis, the upper stone resting solely by gravity on the worn: which is supported on the lower grinding stone. r

In testimony whereof I have hereunto at fixed-my signature.

lVARREN F. FRASER. 

